Standard 16: Understands the ways elements and compounds are classified/organized

The periodic table was not created by one scientist. It is a collaboration of decades upon decades of work and is organized for a very specific set of reasons. It's important to note before we discuss how the table is organized, that not only COULD it be organized differently than it is today, but many scientists actually WANTED it organized differently.

Fist and foremost, the elements on the table are placed in order of their "atomic number" (how many protons the atom has) from lowest to highest. But that is not all, because if it were simply organized that way, the table would be a straight line. 

In the table, the elements are arranged into "groups" and "periods". A horizontal row of elements across the table is a period. Each period stands for a ring of electrons. The further left to right you go in a period is how full that ring of electrons is in that atom. The further right you go, the more that atom likes to keep its own electrons. 

A column of elements is a group. Elements in a group have similar arrangements of electrons, making them have similar chemical properties. For example, the group to the far right is the noble gases, which almost never bond with other atoms and they are all gases at room temperature.